CO2 is it worth it?

[CL2]

My Pools always have low TA. I am thinking about switch over from MA to CO2
Is any one out there using CO2?
What are some of the Issues you have had?

 

[ajw22]

How low is "low TA"?

You may want to read...

Pool Tip #18: Use of Carbon Dioxide for pH Control | Aquatic Consulting Services

 

[JoyfulNoise]

That article is wrong. Adding CO2 does NOT increase the TA of pool water. The chemistry has been discussed many times but here is our wise guru of all things esoteric and other-worldly , @JamesW, explaining it (see Post #10) -

Co2 for PH control

I have been using the BBB method for several years now and always seam to have high PH. Everyone in this form says liquid chlorine doesn't drive up PH but i seams too in my pool. I have a 25,000 gallon plaster swimming pool and i use a Stenner 3GPD pump with a 7.5 gallon tank. I inject my liquid...

www.troublefreepool.com

 

[JamesW]

My Pools always have low TA. I am thinking about switch over from MA to CO2
Is any one out there using CO2?
What are some of the Issues you have had?

In my opinion, CO2 is not a good choice.

If your TA is constantly going too low, you're keeping the pH too low.

What pH are you targeting?

Switching to a pH of 7.8 to 7.9 should help keep the TA and CSI (for concrete pools) in a good range.

Are these commercial pools?

Are you using acid feeders with pH monitors?

 

[CL2]

In my opinion, CO2 is not a good choice.

If your TA is constantly going too low, you're keeping the pH too low.

What pH are you targeting?

Switching to a pH of 7.8 to 7.9 should help keep the TA and CSI (for concrete pools) in a good range.

Are these commercial pools?

Are you using acid feeders with pH monitors?

My TA is starting out low and going lower.
My source water only has a TA of 50.
I am trying to keep my PH as close to 7.4 as I can (gotta keep the kids happy and no burning eyes)....but with my low TA there is some ph bouncing going on.
These are commercial pools and I do have automatic feeders, and I keep my probes clean.
By the time I test my water with out adding a few hundred pounds of baking soda, my TA usually drops to about 30-40ppm.

 

[JamesW]

Try keeping the pH as high as possible within the limits of what you are allowed.

A higher pH won't cause any eye discomfort.

Note that pH "bounce" is mostly a myth. pH doesn't just "bounce" around for no reason.

If your pH is going back up, it's due to adding baking soda to increase the TA.

 

[JoyfulNoise]

The eye discomfort is usually from chloramines forming when chlorine comes in contact with the human tear ducts and conjunctiva. Rubbing eyes tends to force the chlorinated water deeper into the surrounding tissues making the irritation much worse. Blinking instead of rubbing or wearing swim googles will alleviate the problem. Since this is a commercial pool I suspect you have zero or very little CYA in the water and you are keeping your FC levels in the range of 1-3ppm. If that is the case, then pH and TA adjustments really don’t matter.

 

[CL2]

The eye discomfort is usually from chloramines forming when chlorine comes in contact with the human tear ducts and conjunctiva. Rubbing eyes tends to force the chlorinated water deeper into the surrounding tissues making the irritation much worse. Blinking instead of rubbing or wearing swim googles will alleviate the problem. Since this is a commercial pool I suspect you have zero or very little CYA in the water and you are keeping your FC levels in the range of 1-3ppm. If that is the case, then pH and TA adjustments really don’t matter.

My CCL Usually runs around .2-.4ppm and they are indoor pools so I am not using any CYA.
FC is usually between 2-3ppm in case of a Fecal Incident.
My main reason for wanting to boost my TA is I am sitting a little negative on the Saturation Index.
I had hoped using CO2 might make for a relatively easy fix.
It does sound good on paper but no one in my area is using it. (probably a reason for it)

 

[JoyfulNoise]

Yeah, that’s the downside of running a commercial pool with no CYA and high FC levels. CYA isn’t just for sunlight issues, you can and should, if allowed by code, consider using at least 20-30ppm. CYA acts as a chlorine buffer and reduces the concentration of hypochlorous acid (HOCl) to levels that are adequate for sanitation and disease transmission but not so high that you get bather discomfort. Without CYA around to buffer the various reactions of nitrogen with chlorine, the tendency is for the chlorine to form the most reactive and harshest combine chlorine compound - nitrogen trichloride. Nitrogen trichloride is extremely irritating even at parts per billion levels and it is the compound responsible for the “nasty indoor commercial pool” smell. So using CYA has benefits far beyond UV loss. Your county health code would have to not ban its use (some counties do).

Just so you know, 2ppm FC with 0ppm CYA has about 15X as much HOCl than water with 3ppm FC and 30ppm CYA.

 

[Bama Rambler]

Unfortunately Iowa doesn't allow any CYA to be in public indoor pools. However there is an exception.

15.1(2) These rules do not apply to a swimming pool or spa operated by a homeowners association
representing 72 or fewer dwelling units if the association bylaws, which also apply to a rental agreement
relative to any of the dwelling units, include an exemption from the requirements of this chapter,
provide for inspection of the swimming pool or spa by an entity other than the department or a local
inspection agency, and assume any liability associated with operation of the swimming pool and spa.
The association shall notify the department in writing if the association bylaws are amended as above.
The inspector designated by the association shall be a certified operator as defined in 15.3(1). A report
of the inspection shall be filed with the association secretary and shall be available to any association
member on request

So unless you fall under the exception, you're pretty much stuck with zero CYA.

 

[JamesW]

The only time that using carbon dioxide is worth considering is if you're forced to use an arbitrarily high TA (80 +) and an arbitrarily low pH (7.4 or lower).

In that case, you're in a no win situation.

It creates a lot of carbon dioxide in the water that offgasses and raises the pH.

If you reinject carbon dioxide, you can maintain a stable pH and TA.

However, the cost is high and it's really a huge waste of money.

If you're allowed to use a higher pH (7.8 +) and a lower TA (60 or lower), you can minimize the amount of carbon dioxide in the water and the associated pH rise from offgassing.

Even if you do use carbon dioxide, maintaining the pH as high as possible and the TA lower can significantly reduce the amount of carbon dioxide needed.

 

[JoyfulNoise]

The only time that using carbon dioxide is worth considering is if you're forced to use an arbitrarily high TA (80 +) and an arbitrarily low pH (7.4 or lower).

In that case, you're in a no win situation.

It creates a lot of carbon dioxide in the water that offgasses and raises the pH.

If you reinject carbon dioxide, you can maintain a stable pH and TA.

However, the cost is high and it's really a huge waste of money.

If you're allowed to use a higher pH (7.8 +) and a lower TA (60 or lower), you can minimize the amount of carbon dioxide in the water and the associated pH rise from offgassing.

Even if you do use carbon dioxide, maintaining the pH as high as possible and the TA lower can significantly reduce the amount of carbon dioxide needed.

As long as you do that and purchase offsetting carbon credits, the pool can be advertised as a “green” pool ..... although advertising “green” & “pool” might significantly reduce your clientele base ?

 

[JamesW]

CO2 is a useful solvent for extracting chemicals from plants.